Adenylate cyclase and the glucagon-receptor complex have been solubilized from rat liver plasma membranes with Lubrol. The solubilized material was chromatographed on ultrogel columns to give about five-fold purification of the enzyme. The glucagon-receptor and complex separated from the enzyme on the column. Both enzyme and receptor-hormone complex remained susceptible to the actions of guanine nucleotides, suggesting that the receptor and enzyme were each associated with a guanine nucleotide regulatory site. This possibility was investigated further with studies on the membrane-bound forms of these components. It was found that the effects of guanine nucleotides on receptor and enzyme were exerted through functionally different processes as revealed by differences in potency of analogs of GTP, different effects of chelators and phospholipases on the two processes, and differences in reversibility of the actions of Gpp(NH)p on enzyme activity and receptor binding. These findings have been incorporated into a kinetic model that may explain the role of the nucleotide regulatory components in the "coupling" of receptor and enzyme, and in the overall regulation of enzyme activity. BIBLIOGRAPHIC REFERENCE: Yamamura, H., Rodbell, M. and Fain, J.N.: Hydroxybenzylpindolol and Hydroxybenzypropranolol: Partial Beta Adrenergic Agonists of Adenylate Cyclase in the Rat Adipocyte. Mol. Pharmacology 12 693-700, 1976.